1. Field of the invention
The present invention relates to a method for manufacturing layered capacitors having a thickness of inactive layers.
2. Description of the Prior Art
For various reasons (electrical or physical insulation, protection, preserving a stack), it is sometimes necessary, during the manufacture of a layered capacitor, to wind a certain thickness of inactive layers This has come to light with the technology now currently used for winding metallized dielectric films onto a wheel with a large diameter. The films are, for example, metallized on one face, except for a lateral margin. In order to obtain a mother capacitor, it is then possible to wind two of these films onto a wheel in order to form a stack, the margins being alternated and a lateral projection of the metallized parts being provided in the stack produced. The component capacitors consisting of a dielectric film between two metallizations are combined in parallel by metallization or Schoop-coating of the lateral faces of the stack.
If it is desired to wind a certain number of inactive layers about these two layers, which will form the active parts of capacitors, various procedures are possible at present.
The technique of demetallizing a plastic film coated with a metal layer (which is generally aluminum in the case of capacitors) under the influence of an electric arc is known. This method is widespread. A major disadvantage of it is that it rapidly contaminates the demetallizing system.
The technique which consists in inserting, during the winding, layers of non-metallized, and therefore non-active films is also known. This method is poorly compatible with high-speed production and in particular with winding onto a wheel with a large diameter. Indeed, it requires stopping the winding machine and frequent manual interventions.
In order to overcome these disadvantages, the invention provides a novel method which has the advantage of producing a winding of inactive turns with no demetallization, without stopping the machine and with no spontaneous breaks of the film. This winding of inactive turns is obtained from films used for producing the active parts of the capacitors and as a result of a lateral displacement operation without stopping the winding operation.